1 2 Previous Next 16 Replies Latest reply on Jul 26, 2012 5:36 AM by user_14586677



      Hello Sir/Mam,


                                I am using CY8CKIT-001,i want to connect microphone and speaker to the PSoC3 ,may i know what should be the specifications of Speaker and microphone required to connect to PSoC 3.

        • 1. Re: Mcrophone,Speaker

          Can you tell us what you want to with that? Otherwise it is just looking into a crystal ball :)


          For the microphone, a pre-amplifier might be needed (e.g. if you use a pure electret microphone capsule). For the speaker - you cannot source more than 25mA of current. So the speaker nees to have a high enough impedance if you want to connect it directly (130 ohms when using 3.3V).

          • 2. Re: Mcrophone,Speaker

            There is a wide range of performance vs technology in mics and speakers.




            You should consider getting samples of mics and speakers, using mike and


            speaker simple amplifier, hook them up and evaluate sound perfromance. Then


            once you get that done work on interface circuits.




            Here are some ap notes to look at -












            Regards, Dana.

            • 3. Re: Mcrophone,Speaker

              Here i want to connect the microphone to PSoC ,digitize the microphone output and store the values in memory of PSoC and i should hear  the sound signal using  speaker ,where speaker input is the output of the DAC(PSoC peripheral).


              so i just want to know the specifications of Microphone and speaker to get better result using PSoC..

              • 4. Re: Mcrophone,Speaker

                There is no simple answer here. The questions that have to be answered -




                1) What power level do you want out of the speaker ?


                2) The above drives the technology to some extent ?


                3) Hi fidelity, or phone grade, or something in between ? What is the frequency response you


                want out of Mic and Speaker ?


                4) External amps or strictly onboard solutions ? 1) has a great impact.


                5) Speaker or ear buds, affects needed power.


                6) Are you doing speech recognition ? If so fidlelity, at the very least repeatability


                very salient discussion here.




                Hopefully someone can give you a recomendation, but until you decide


                whats is acceptable, specs of some sort, you are treading water so's to speak.




                I am not being disrespectful when I say you have asked what car should I


                buy, and given the forum no other requirements. Does it have to have 4 wheels,


                wings, engine........




                Regards, Dana.

                • 5. Re: Mcrophone,Speaker

                  If you want to just play around:

                  • try to get a microphone which delivers line level (1V or so) - this saves you the need for an amplifier, and you get less noise (you can use an PSoC-internal amp, but the noise is higher then)
                  • use simple head-phones as speakers. Measure their impedance, and maybe add some resistors to get at least 130 ohms (200 would be better)
                  • 6. Re: Mcrophone,Speaker

                    Just a thought, if you first do the homework, that is eliminate poor quality mics and speakers,


                    get good quality parts, do whatever it takes to do interface, you have eliminated, temporarily


                    the transducers from the evaluation. By doing this you can see what PSOC and various sample


                    rates/compression will be required. Then you can work on "dumbing" down the transducers,


                    mic and speakers, cost and quality, until you have reached unacceptable performance.




                    Regards, Dana.

                    • 7. Re: Mcrophone,Speaker

                      If you just want to test, you can use the speaker as the microphone, so you don't need a buy a microphone. Test the hardware first(ie build hardware to amplifier the signal from the MIC, and feed the output to another speaker (with series resistor). one you get good level. then use a pure sine wave as the souce for recording into the PSOC memeory and play back the tone. Once that is done. Then try to use the MIC to test. Do it one step a time

                      • 8. Re: Mcrophone,Speaker

                        basically microphone take maximum 1v signal.so use a buffer circuit to develop your hardware

                        • 9. Re: Mcrophone,Speaker

                          Zelscope is a Windows software that converts your PC into a dual-trace storage oscilloscope and spectrum analyzer.




                          reference website:






                          u have to use this circuit to couple microphone

                          • 10. Re: Mcrophone,Speaker

                            Microphone interface circuits are specific to the technology being used for


                            the mic itself. Generally their datasheets have an interface circuit targeted towards


                            the mic element being used, and make compromises in the freq response plot of the


                            mic to "flatten" it or remove objectionable peaking.




                            One size does not filt all.




                            Regards, Dana.

                            • 11. Re: Mcrophone,Speaker

                              Don't use this circuit to connect your microphone to the PSoC! I creates up to 12V on its output, which will destroy your PSoC.


                              You need to get "line level" - which is about 1V (this is what gets delivered by a typical cinch output). Use either a microphone with integrated preamplifier, or get one suitable for your microphone.


                              If you really want to save money, and are willing to experiment: use a headphone as microphone. Connect it to a PGA on the PSoC with the highest amplification. This might be enough for basic experiments (I did not try it).

                              • 12. Re: Mcrophone,Speaker

                                You you wants to test your SW only you can also use the line in and line out from the PC, you can adjust the levels easily. This way you don't need to worry about the hardware issue first. Fix you SW then come back the hardware.

                                • 13. Re: Mcrophone,Speaker

                                   Since the output from a mic or any other audio device will be AC you will need to bias it to avoid driving any PSoC pin below the specified maximum (or minimum) levels.


                                  Basically you want to take the output from a MIC, amplify it to some level range that suits the ADC in the PSoC, and bias it to ensure it does not clip at the top or bottom range. Then sample the ADC, store the values in RAM.


                                  For the output you need to take the output from the ADC and buffer it and amplify it to some level strong enough to drive your selected output device. You could consider using a piezo transducer instead of a speaker?

                                  • 14. Re: Mcrophone,Speaker

                                     Of course in the ouput I meant to type 'DAC' not 'ADC' :-)

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